ACTA1 and cancer: This results in a CAF phenotype, that can be defined by its elongated spindle morphology, absence of epithelial or endothelial markers, expression of mesenchymal markers (vimentin, α-smooth muscle actin (α-SMA), fibroblast activation protein (FAP), or platelet-derived growth factor alpha (PDGF-α)), and absence of mutations associated with cancer.